There are many occurrences where foot and vehicle traffic needs to be selectively and rapidly changed to permit passage in one situation, and to prevent passage in other situations. The changes in situations may result from severe weather, disaster, public events, etc., in which when, or even where the change in traffic is hard or impossible to anticipate or control when needed.
Furthermore, the typical gate systems are complex, too cumbersome for 1-person operation, or simply not placed where needed, to effectively control the traffic situation where needed. Moreover, the corresponding costs further reduce or interfere with the usage of gates, resulting in an under- or non-controlled traffic flow.